Is there any special tuning needed to use Sunoco 110 with a 72 800 cfm QJet? Seems rich at idle and I didn't know if it was from "good" gas or not. No nozzle drip or obvious flooding. o No:
Nope, I wouldn't expect you should have to do anything different to the carb with no changes other than the fuel. First time trying the 110 fuel? Tank empty before you ran it? What fuel did you run previously? Did it come from a pump or barrel or gas can, etc.? Devon
I have the exact same carb. The only tuning I've done to the carb was to install richer secondary metering rods, but not because of use with race gas, my motor is just plain hungry at WOT and I needed to in general. Only other mod I've done is get in a nail it.
Ha-ha!! Nope, I just tapped a 55 gallon drum a couple of months ago. I have a 67 427 Vette in my shop right now. It was stored for 8 years (!) and when I recommissioned it, besides a new battery and oil change, it started right up and runs fine!~! Not saying the owner should go to the track with 8 year old gas, just saying tho... I'm mixing 93 and 110. The 494 in my convertible has 11.4:1 cr and is a fresh combo last year. I've ran about 25 gallons of 110 through it so far this year.
I, re-tune the idle mixture screws when I change octane. I set the screws to get max vacuum when in gear at spec idle speed. Block the wheels and dis-connect the vacuum advance while you set this.
Hi Bob, when i run a full tank of Sunoco 110, the plugs start to load up after about half the tank is used. So, over the years of experimintation of mix %'s, i found that my engine runs best on no more than 50/50 110 to 93. I recall back in the early 70's, when i had my '68 GTO with 11:1 compression, it too, would load up on the highest octane from the Sunoco pumps, just too much lead i suppose. I had to use a grade below the highest and it would run great.
Well, it started to rain the other day and I didn't have a chance to get into more. I'll get it resolved and post what it was.
How do the spark plugs look Bob? The day I drove my car around with the bad gas, it drove OK, just a bit rough at idle, and reduced vacuum, and it smelled pig rich, but no signs of flooding. I had it on the highway, and it had plenty of power. When I removed the plugs, they were all black. My plugs never look like that, and haven't since.
I took the air cleaner off and that's about it so far. Idles much better with a vacuum leak. Carb was done by Fred Catlin 100 years ago and sat on a shelf for about the last 6 years. Ran perfect all season until about last week. May not even be a carb problem. I haven't adjusted the valves since I put the engine in about 500 miles ago. Cam is a solid flat tappet.
Sean, Even though those screws are commonly called idle mixture screws, they really have nothing to do with how rich or lean the actual idle mixture is. That is determined by the idle restriction, and air bleed sizes. When you turn the screws, you are simply allowing more or less of the mixture to enter the air stream. Maybe turning them in would help.
Fixed - valve adjustment took care of it. I was surprised that they can change so much. Cam is a TA 210S-HL solid flat tappet. Ironic that a solid cam is quieter than the last 3 hydraulic ones I've used. Note to self - check valve lash yearly. :Smarty:
